Microgroove-Structured PDA/PEI/PPy@PI-MS Photothermal Aerogel with a Multilevel Water Transport Network for Highly Salt-Rejecting Solar-Driven Interfacial Evaporation

Desalination of seawater through solar-driven interfacial evaporation is an efficient approach to solve the freshwater resource shortage problem. However, the salt formation and crystallization during interfacial evaporation limit the long-term stability of the solar evaporator. To further improve the salt-rejecting capability of the solar evaporator, we developed a porous framework photothermal microgroove-structured aerogel (PDA/PEI/PPy@PI-MS MGA, pppMGA) through a combined freeze drying, laser engraving, and chemical polymerization technique. A multilevel water transport network consisting of a three-dimensional (3D) skeleton, a microgroove-structured water channel, and a cotton core is constructed, which can effectively improve the salt-rejecting capability of the aerogel. At the same time, the combination of the 3D porous microgroove structure of the pppMGA evaporative interface and the efficient light absorption capacity of PPy effectively increases the vapor–liquid evaporation area and the light absorption rate (98%). A high evaporation rate (∼1.38 kg m–2 h–1) and high photothermal conversion efficiency (∼93.04%) can be achieved on the pppMGA evaporator under 1 sun illumination, which can operate stably in high salt concentration (20%) water for 8 h. Even under 3 sun illumination and a 20 wt % NaCl solution, the pppMGA evaporator can operate stably without salt crystallization. Such a photothermal aerogel with high salt-rejecting performance provides a new avenue for designing an interfacial evaporation system that can operate stably under high salt concentration conditions.